Draftsman&#39;s triangle.



F. I. DU PONI.

DRAFTSMANS TRIANGLE.

APPLICATION FILED 14111.4, 1911.

1,012,340. Patented Dec. 19, 1911.

2 SHBETSBHEET 1.

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P, I. DU FONT.

DRAFTSMAN'S TRIANGLE.

APPLICATION FILED MARA, 1911.

1,012,340. Patented Dec.19,1911.

2 SHRIMP-SHEET 2.

. ATTORNEYS.

FRANCIS I. DU FONT, OF WILMINGTON, DELAWARE.

. DRAFTSMANS TRIANGLE.

Specification of Letters Patent.

Patented Dec. 19, 1911.

Application filed March 4, 1911. Serial No. 612,220.

To all whom it may concern:

Be it known that I, FRANCIS I. DU Pour, a citizen of the United States,residing at Wilmington, county of New Castle, and State of Delaware,have invented a new and useful Improvement in Draftsmens Triangles, ofwhich the following is a full, clear, and exact description, referencebeing had to the accompanying drawings, which form a part of thisspecification. 1

The object of my invention is to provide a draftsrnans triangle orsimilar instrument capable of being superimposed upon, and moved over,the face of a drawing or tracing in course of execution, regardless ofwhether the ink beneath the triangle is dry, and without appreciablyaffecting such of the inked lines as may not be dry, thereby effecting agreat saving of time in the completion of the work.

In the drawings: Figure 1 is a plan View of a triangle embodying myinvention; Fig. 2 is an inverted plan view of the same; Fig. 3 is anenlarged plan view of a detail of Fig. 2; Fig. 4 is a section on theline 4-4: of Fig. 8; Fig. 5 is a vertical section of a modification;Figs. 6 and 7 are respectively plan and edge views of a modified form ofwheel.

a is the triangle. In recesses in the three corners of the triangle areinserted cupshaped platesb having annular flanges c. The flanges areflush with one face of the triangle and may be secured to the same byscrews (Z. The base of the cup extends somewhat beyond the plane of theopposite face. Cup-shaped recesses are thus formed in one face of thetriangle. Secured to the base of each cup is a pivot-pin c. This pinextends at right angles to the plane of extension of the cup. Rotatablymounted on each pin is a bracket f having a forked end in which issecured a pivot pin g. Rotatably mounted on each pin 9 is a wheel,roller or caster, it. This roller is provided with a knife-edge andprojects beyond the plane of the recessed face of the triangle.

In use, the triangle is placed upon the drawing or tracing with itsrecessed face down and the rollers therefore in contact with the paper.The triangle may be freely shifted over the face of the paper in anydirection and the rollers may roll over inked lines without blotting orspreading the ink because of the incapacity of the knife edge to pick upenough ink to make an appreciable mark. At the same time, the trianglemay be held steadily in a given position without great downward pressureupon the same.

It will be understood that by the term knife-edge I do not mean an edgeso sharp as to actually out or groove the paper, but the term is used incontra-distinction to an edge possessing a flat convex or sphericalperiphery of appreciable or substantial width or area and in its mosteffective embodiment will be a knife edge that might be fairlyaccurately described as dull.

In Fig. 5, I have shown a modification in which the underside of thetriangle or ruler z' is hollowed out for lightness (forming in effect asingle recess) and the edge is brought to the desired proximity to thepaper. A lip 7c is provided to facilitate picking up the triangle orruler with the fingers. The wheels m are similar in construction andmounting to the wheels lb.

In Fig. 6, I have shown a modified form of wheel a, in which a series ofknife-edges 0 are arranged spirally like a spiral gear around theperiphery of the wheel.

Other modifications will suggest themselves to the skilled mechanic, theembodiments hcreinbeforc described being merely illustrative.

WVhilc I have described the invention as applied to a triangle, it willbe understood that it is also applicable to other analogous instruments,such as rulers, T-squares, section-liners, etc.

Having now fully described my invention, what I claim and desire toprotect by Letters Patent is:

1.. A drafting instrument comprising a plotter having ruling edges andmembers attached thereto projecting beyond the plane of one face of theplotter and adapted to freely roll upon the paper in all directions atany angle to said ruling edges, said members having parts of negligiblearea adapted to contact with the paper and parts immediately contiguousto the contact parts arranged at sharp angles thereto.

9.. A drafting instrument comprising a plotter having ruling edges andknife-edged rollers each projecting beyond the plane of one face of theplotter and adapted to freely roll upon the paper in all directions atany angle to said ruling edges.

3. A drafting instrument comprising a plotter, having ruling edges,brackets, each revoluble on the plotter on an axis at a right angle tothe plane of extension of the plotter, and a knife-edged .Wheelrevoluble on each bracket on an axis: parallel to the plane of extensionof the plotter and projecting beyond the plane of one face thereof.

4:- A drafting instrument comprising a plotter having ruling edges,edges above the ruling edges to facilitate handling, and knife-edgedrollers adapted to roll in any direction and supporting the plotter outof contact with the paper.

5. A draftsmans instrument comprising a triangular plotter andknife-edged rollers located respectively near the three corners 5thereof and adapted to roll in any direction and support the plotter outof contact with the paper.

In testimony of Which invention, I have hereunto set my hand atWilmington, Del, 20 on this 1st day of March, 1911.

FRANCIS I. DU PONT.

Witnesses:

G. L. NAYLoR, WM. P. NVHITE.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

